An angiography in which lesions on blood vessels are diagonosed by injecting a contrast medium into the blood vessel and studying the flow and expansion of the contrast medium and a topical administration therapy in which therapeutic liquid is injected into the blood vessel have been widely carried out by the development of Seldinger's method in which catheter is inserted into blood vessel transdermally.
Heretofore, the catheter used for injecting therapeutic liquid into lesions on blood vessels has been used by firstly introducing a guide wire thereof within the blood vessel near the lesion and then inserting the catheter along the outer wall of the guide wire. As the guide wire, in general, a metal guide wire of stainless steel and stainless steel coil has been used and has drawbacks such as liability to injuring the inner wall of blood vessel during operation. Recently so called flow guide wire, of which tip is floated on the blood flow and introduced into peripheral blood vessels, has been proposed, but it also has drawbacks, for example, in which the structure is so fine that it is difficult to pass through such blood vessels having many windings and bendings and it is substantially impossible to introduce it up to a lesion of peripheral blood vessels. Also, a guide catheter which can perform the roles of both catheter and guide wire and well known leak balloon catheter have drawbacks, for example, the liability to injuring the inner wall of blood vessels, the difficulty of passing through peripheral blood vessels and the instability of the operation.